1. Technical Field
The present invention relates to a lentiviral vector system and a method of gene transfer and gene therapy using the viral vector system, wherein the viral vector system is pseudotyped by a viral vector having an excellent retrograde transport ability particularly in the brain and having high production efficiency, in particular, a fused polypeptide comprising an extracellular domain and a transmembrane domain of rabies virus glycoprotein (RV-G) and an intracellular domain of vesicular stomatitis virus glycoprotein (VSV-G)
2. Background Art
Non-proliferative (non-replicating) recombinant lentiviral vectors are used in a number of studies as a vector for gene therapy to treat various diseases, such as a system which transports a target gene to a non-dividing cell in the central nervous system (CNS) and maintains its expression over a long period of time (Nonpatent Literatures 1-4). In particular, a primate lentiviral vector from HIV-1 (human immunodeficiency virus type 1) is the most proven vector for gene therapy (Nonpatent Literatures 5-8).
On the other hand, for gene therapy of a certain cranial nerve disease, useful is a viral vector which can infect a nerve terminal, is retrogradely transported through an axon and introduce a target gene into a cell body in a target site located far from the infected site (FIG. 1).
To date, as an envelope glycoprotein (an envelope gene protein), a retrograde transport system in the brain of cynomolgus monkey was developed using a recombinant HIV-1 virus which uses (is pseudotyped by) a vesicular stomatitis virus (VSV) glycoprotein (VSV-G), but the retrograde transportation of the vector was not efficient (Nonpatent Literature 9). In the method described in the reference, very few cells in the central nervous system were retrogradely infected with the recombinant HIV-1 virus injected into the striatum of the monkey, as indicated by immunostaining.
On the other hand, rabies virus (RV) is known to have an activity that RV infects a synapse terminal, and is retrogradely transported through an axon. Indeed, there is a report that a retrograde transportation ability of a non-primate lentiviral vector based on equine anemia virus was promoted by RV-G (Nonpatent Literatures 10 and 11, and Patent Literature 1).
Further, HIV-1 lentivirus pseudotyped by RV-G has been reported (Nonpatent Literature 3), but, in that report, an animal experiment (in vivo) was not actually conducted using that viral vector. In addition, gene transfer in CNS with a HIV-1 vector pseudotyped by a glycoprotein from Mokola lyssavirus, a neurotropic virus causing rabies, or VSV-G has been studied. As a result of the nasal injection of the HIV-1 vector pseudotyped by the Mokola lyssavirus glycoprotein or VSV-G into a rat, these vectors were mutually comparable with regard to retrograde transportation to the olfactory nerve system (Nonpatent Literature 12). In addition, in that literature, an example in which a viral vector was administered through striatum was not described.
To date, the present inventors have revealed that highly-frequent retrograde gene transfer at various regions in the brain can be feasible by preparing a HIV-1 lentivirus vectors pseudotyped by rabies virus glycoprotein gene (RV-G) (RV-G/HIV-1 vector) (Patent Literature 2, Hum. Gene Ther., 2007).